There are many types of structures, for example bridges and viaducts that carry a road surface such as a railway or highway at a height sufficient to be dangerous should a person working on such a structure fall. Since it is inevitable that such structures will require maintenance, repair or modification, it is likewise inevitable that certain personnel will be exposed to this danger. In order to minimize the danger, both the Occupational Safety and Health Administration (OSHA) and the Federal Railroad Association (FRA) have introduced regulations to help ensure the safety of these personnel. Typically, scaffolding or nets are required to be placed along the sides of a bridge or other structure. However, such scaffolding or nets are relatively expensive, particularly in instances of short term repair work or inspection.
In the instance of railway bridges or other structures, it has been suggested that personnel can be tethered to a rail. In the event of a mishap, the tether would safely suspend a person from the rail and permit rescue. Thus, the restraint device connecting the tether to the rail must be strong enough to withstand the shock loads created by a falling person and remain affixed to the rail. As a result, such a restraint device is quite heavy. In order to increase the mobility of the person working on the structure restraint devices having sets of upper and lower rollers to permit the restraint device to be moved along the rail. Such designs are unwieldy, however, since it is a relatively complicated procedure to assemble the rollers and restraint device to the rail. Finally, the known designs suffer from the further drawback of having two sets of vertically spaced-apart rollers, which limit the use of a restraint device to rails of certain maximum rail head or minimum height dimensions.
It would therefore be desirable to provide an improved restraint device to tether a person to a rail. Accordingly, it is an object of the present invention to provide a restraint device that is easily engaged with and removed from a rail that is designed to enhance the mobility of the tethered person. It is a further object of the present invention to provide a rolling restraint device which is readily adapted to rails of almost any size.